But there's another interesting release that always gets less attention — at the same time, the Department for Work & Pensions releases the number of new National Insurance numbers issued to overseas nationals. An NI number is pretty crucial if you want to work in the UK legally.

The figures are broken down by regions, and even go down to specific local areas. But the thing that stands out most of all is that London is overwhelmingly more popular than any other region in the UK.

Mike Bird, Business Insider, DWP

There are more than three times as many applications from migrants for NI numbers in London (in comparison to the size of the existing population) than anywhere else in the country.

The NI numbers might offer a better view of what's happening to the British labour market than raw immigration figures, since they're only counting adults, most of whom presumably want to work. In the year to September, there were 862,000 registrations, 194,000 more than in the previous year.

39% of those were in London, as opposed to more like 13% of the total population of the country. There are some London boroughs that issue more NI numbers to migrants than Wales does.

Because London's a bigger region than most, the graph is even more weighted towards the capital when the size of the existing population isn't taken into account: